The present invention relates generally to a dual wheel driven cycle and, more particularly, to a kit for converting a conventional bicycle, motorcycle, dirt bike, or the like, to a dual wheel driven cycle.
The kit according to this invention includes a sprocket connectable in fixed relation to the conventionally non-driven front wheel of a conventional cycle for conjoint movement with that wheel. A drive gear is mounted on either the pedal gear or chain of the cycle and receives power from the pedal gear or chain on which it is mounted. The kit provides a cable gear mountable with respect to the cycle's frame and meshable with the front wheel sprocket for driving the sprocket and thus driving the cycle's previously non-driven front wheel. A rotatable cable connects the cable gear to the drive gear. The cable transfers the rotational motion of the drive gear to the front wheel.
The sprocket is capable of at least two alternative constructions. The first construction contains a series of radially spaced concentric slots which engage the teeth of the cable gear. In the second construction, alternating rows of gear teeth and notches or grooves on the sprocket engage the cable gear teeth.
The sprocket may be attached to the conventionally non-driven wheel in at least two ways. The kit may include clips for securing the sprocket to the spokes of the non-driven wheel. Alternatively, the kit may include a sprocket having a rigid shaft formed integral with the sprocket in order that the sprocket may be mounted onto the axle of the non-driven wheel. The sprocket has a central passage for aligning the sprocket with respect to the axle of the non-driven wheel.
The kit also includes gear support structure fixable to the bicycle frame for supporting the drive gear in relation to the pedal gear or chain of the cycle. Plastic straps are provided to secure the drive cable to the frame. A spread clamp is provided to attach the cable gear to the frame. Finally, a control lever is attached at one end to the gear selector of the cycle and at its other end to the cable gear; the lever moves the cable gear relative to the sprocket in response to operator gear selection. This allows speed synchronization of the previously non-driven, but now-driven, wheel with the driven rear wheel. It also allows the now-driven front wheel to operate at a variety of speeds.
The invention has a wide variety and range of applications and uses. It is particularly useful on bicycles having single, three, or ten speed gear selections. The elements of the kit are placed in cooperation with the parts of the bicycle. Through standard operation of the bicycle parts, the kit elements drive the bicycle's normally non-driven wheel and create a dual driven cycle.
Presently known devices for driving the wheels of a cycle abound. These devices include combinations of levers and gears which allow the operator to drive the rear wheel. They encompass a variety of drive transmissions, conventional derailleur and other mechanisms, which adjust the transmission ratio between the rear driven wheel and the pedal gear. Some of these devices are removable and permit cleaning, repairing, or mounting on existing bicycles.
One device, that is disclosed in U.S. Pat. No. 4,029,332 issued to Harry C. Davis, is a rotacycle. This rotacycle includes a two-wheel friction drive. The automatic, variable-speed transmission of the rotacycle has a central rotor in friction-tight contact with a plurality of pulley wheels. These pulley wheels are flexibly connected with mating wheels to impart torque to the perimeter of the first and second wheels.
All of these devices may be grouped, however, into two categories. The first category includes devices which can be adapted for use on conventional cycles. Such devices often require time, a number of steps, skill, and perhaps a variety of tools to connect and disconnect the device and cycle.
Moreover, devices in this first category usually are expensive to manufacture and difficult to maintain. They include an array of obstructive cables and protruding levers. Most importantly, none of these devices drive the second wheel of the cycle.
The second category of known devices for driving cycle wheels includes those which drive both cycle wheels. These devices are not adaptable with conventional cycles; rather, they represent separate, complete mechanisms. In addition, friction-tight mating surfaces are the driving elements in these devices, and friction usually causes wear and prevents durability.
Adaptable for use on conventional cycles or not, none of the presently known devices includes elements that receive power from the conventional cycle's existing drive chain and use that power to drive the cycle's second, non-driven wheel. Absent such elements, none of the presently known devices can attain the advantages of the present invention.